Skinning machine



Mrch 18, 1952 F. J, coAD sxnmmc MACHINE 4 Sheets-Sheet 1 Original Filed July 18, 1944 INVENTOR.

I N VEN TOR. Fi'ederic J: Coed, deceased BY Swi ft 1; Company, Assjgrze BY M422 ATTOIZN -r March 18, 1952 F. J. COAD Re. 23,471

SKINNING MACHINE Original. Filed July 18, 1944 4 Sheets-Sheet 5 FIG;5

1gifl H'eq'eric J (bad, dece asen BY Swift 4! C'ompmg dssyaee F. J. coAo SKINNING MACHINE March 18, 1952 4 Sheets-Sheet 4 Original Filed July 18. 1944 INVENT R. Fidel-1c J. C0114 deceased BY Swaff [om m ,45i7nee WAR ATToR EY Reissued Mar. 18, 1952 SKINNING MACHINE Frederic Goad, deceased, late of Des Moines,

Iowa, by Swift & Company, Chicago, 111., as-

signee Original No.

Serial No.

2,461,466, dated February 8, 1949, 545,474, July 18, 1944. Application for reissue February 6, 1950, Serial No. 142,552

Matter enclosed in heavy brackets I: appears in the original patent but forms no part of this dicates the additions made by reissue.

9 Claims.

reissue specification; matter printed in italics in This invention relates 'to a machine for removing skin from meat cuts and more particularly to a device for forcibly pulling skin from a meat shoulder or ham cut.

It is an object of this invention to provide a machine for pulling skin from a meat cut.

It is another object of this inventionto provide an improved means for removing skin from a plurality of shoulder cuts or ham cuts.

' Other objects will appear below.

In preparing certain meat items for the consumer trade it is necessary that the skin be removed from the cut and particularly is this true when ham and shoulder cuts are prepared for the retail trade with the bone removed. Furthermore skin is a valuable by-product yielding either a high grade gelatin or leather, and, therefore, when supplying large volumes of certain cuts to the hotel and restaurant trade where the skin cannot be utilized it is removed from these cuts for its value as a by-product.

It has been the practice in the past to remove the skins by a cutting operation and mechanical cutting means are available to remove the skin from a fiat slab of meat. When,- however, an irregularly shaped out such as a shoulder or ham cut is to be skinned, it is necessary that a hand cutting operation be performed to effect a separation of the skin.

In removing the skin from an irregularly shaped cut by hand, not only is considerable labor involved but also the labor must be quite skilled. If the skin is to be used in the preparation of leather, it must be removed in an undamaged condition and yet it is desirable to separate the skin from the out without leaving any meat or fat clinging to the flesh side of the skin. It is seen therefore that the most efficient removal of the skin requires the operator to rapidly sever the skin from the meat cut by slicing through the layer beneath the skin. It is thus readily apparent that considerable practice is required before an operator can perform this relatively delicate operation in a rapid manner.

The present invention has been provided to make available a skinning machine adapted to the removal of skin from an irregularly shaped cut of meatwithout necessitating a cutting operation such as might injure the skin. It provides a means for relatively fixing the meat out while a pulling force is exerted against the skin and, when the pulling force is applied in the right direction, the skin may be peeled off quite effectively without tearing or otherwise damaging the skin.

The machine forming an embodiment of the subject of this invention is shown in the drawings wherein:

Figure 1 represents a side elevation partly broken away of the preferred form of the machine for simultaneously handling a plurality of irregularly shaped cuts during the skinning operation,

Figure 2 represents an end elevation partly broken away of the preferred form of the machine shown in Figure 1,

Figure 3 represents a plan view partly broken away of the preferred form of the machine shown in Figure 1,

Figure 4 represents a side elevation of a second form of the machine,

Figure 5. is a plan view of the machine shown in Figure 4,

Figure 6 is a perspective view of a bifurcated hook element shown in Figures 4 and 5 for engag ing the meat cut [.1

Figure 7 is a side elevation of a form of a machine illustrated in Figure 1 in which the ham cut is moved while holding the skin relatively stationary.

In general, the preparation of lboned shoulder and ham cuts includes a skinning operation. While the present invention finds particular application to the skinning of such portions of a carcass, it will be apparent as the description proceeds that the invention may find use in the skinning of larger cuts and up to one-half and whole carcasses. These ham and shoulder cuts, however, have a generally irregular shape and thus cannot readily be adapted to a machine cutting operation for removal of the skin from around the entire periphery of the cut. The herein disclosed invention is, therefore, particularly adapted to the skinning of cuts of this type by a skin pulling method. When the shoulder and ham cuts are removed from the carcass the shoulder cut, for example, is severed so that the humerus bone extends longitudinally through the cut. The ham is removed in such a manner that the femur bone extends through the cut. Each of the humerus and femur bones of course is formed with an enlarged end where the bones engage the shoulder and elbow joints, or hip and knee joints respectively.

It has been found that the skin may be rapidly removed from such an irregularly shaped cut by a pulling action. When the skin is properly prepared and is forcibly drawn from the cut, the fell layer separates and the skin is stripped off without damage to the meat or itself and it is generally free of all clinging meat and fat particles. This is true with respect to beef and lamb cuts. With pork, however, which has no layer of fell between the skin and the flesh, the skin is similarly peeled off when pulled in this manner.

To remove skins by pulling, in accordance with this teaching, the cut is fixed in a machine designed for a power pulling action whereupon the skin is pulled back upon itself so that itis peeled from the meat. The shoulder or ham cut is prepared for skinning by having a tab of skin lifted up on the outside of the leg" cut so that it may be engaged by suitable clamping means and, in

addition, the skin is just cut through along a line generally parallel with the longitudinally extending bone of the cut on the inside portion of the leg of the animal. made so that only the'skin is cut. The incision need be no deeper.

When pulling the skin from the cut it has been found that the most satisfactory skin removal results from engaging the skin in a manner such that it is ripped from the cut by reversing the skin upon itself. The fell layer ofbeef or lamb, for example, is more quickly broken by this procedure because the pulling force is always directly applied to the fell at the fold as the skin folds over upon itself. The fell is comprised of many small fibers interlaced and bonded to the skin and flesh. This manner of pulling exerts a maximum pull against a fewer number of fell fibers than any other method so that the fibers are tensioned and broken before the pulling force can be substantially transmitted and distributed through the flesh or other more remote fell fibers. A similar advantage in directing the application of the pulling force substantially to the line of separation at the fold of the skin is also realized in skinning pork, and the pork skin is easily rolled back upon itself in a mannerto be quickly and easily separated from the flesh-and fat.

A machine adapted to perform this invention is shownin the drawings and referring to Figure 1, ham cut I is shown in position to be engaged by a clamping means to efiect a removal of the skin from the-cut. The ham has femur bone extending therethroughand a skin tab denoted |2. The femur bone lhas an enlarged hip joint end l3 at the butt end of the cut, which may be engagedbetween one of the pairs of the prongs 4 and I5 forming a holding means for a cut on the skinning machine.

The two pairs of prongs l4 and I5 are fixedly mounted on a suitable movable supporting head I6 slidable in the direction of the arrows shown in Figure 2. The head It may be mounted upon guidetracks I1 and I8 for this lateral movement across the machine for a purpose that will appear morefully below, and the two pairs of prongs are supported on the head to hold the meat cut-engaged thereby on table l9. Suitable stiffening arms It may be fixedly mounted on the side of supporting head I6 which faces the frame of the machine, the arms carrying rollers at their free ends to bear against the frame of the machine in order to brace the hooks against the frame of the machine when the skin pulling force is applied. It is to be understood of course that the skin may be slit on the inside of the leg whenthe tab is loosened on the outside before the cut-is placed on thetable and between the tween the one pair of prongs l4 and I5, a' clamp The inside cut is carefully is fixed to the tab |2 by engagement of jaws 2| and 22 whereupon the clamp 20 may then be connected to a driven pulling mechanism.

Qlamp 20 may take the form of a pincher like fievi'ce wherein the jaws 2| and 22 are driven together upon closing of arms 23 and 24. Arms 23 and 24 are normally urged apart, by spring 25 and are closed together when links 26 and 21 are pulled outwardly as when chain 28 is connected to the pulling means, This construction provides a clamping device which is normally urged to position for releasing anythin engaged between the jaws 2| and 22 yet when once engaged, and as long as pulling action is exerted, the jaws tend to engage the skin more tightly as the pulling effort increases. As long as the closing tendency caused by the pulling action is greater than the contracting force of spring 25, the skin will remain firmly engaged between jaws 2| and 22, and the spring tensionis selected to be such that the jaws remain closed until the skin pulling operation is complete.

The flexible link or chain 28 for transmitting the pulling force to the clamp 20 is fixed at one end to a carriage 30. Carriage 30.is provided with a downwardlyextending hookarm 3| adapted for engagement with the driven pullin means. Carriage 30 is designed to slide or ride across thetop surface of the pulling machine and has suitable bearing members32 and 33 for supporting the carriage on this surface or slideway. A slot 34, Figure 3, in thesurface permits the hook arm 3| to extend downwardly therefrom for engagement with the pulling means.

The invention here shown makes use of a pulling means taking the form of a pair of driven chains 44] and 4| carried on suitable sprocket Wheels, These two chains are interconnected at spaced points with cross bars'42 and the upper run of the composite chain structure is positioned below slot 34 to cooperate with the hook arm 3| to drive the carriage forwardly in the direction of the arrow shown as in Figures 1 and 3. The chains 4|) and 4| may be driven from any suitable power source to effect the desired pulling action.

The above described mechanism is operative to engage the skin of any cut fixedly held with respect to chains 40 and 4| so that the skin may be pulled therefrom. A cutmay be laid on the table l9 and engaged in the machine. by forcing the bone between one of the pairs of prongs l4 and I5, as shown in' Figure 1. The head Hiv is then adjusted laterally to place. the cut generally in front of the slot 34 whereupon the jaws 2| and 22 may be closed onto the tab I2 and the chain.

28 pulled to clamp the. jaws. Then th hook arm 3| is dropped down through slot 34 and between chains 4ll and 4| for engagement with one of the cross-bars 42 of the driven pulling means.

When the hook arm is taken up behind one of the cross bars 42, it.is carriedforwardly and carriage 30 rides'forwardly, on the slideway on the upper surface of the frame of the machine. The forward motion of, the carriagejll through link 28 and clamp 20 pulls. the skin off of the cut progressively from one end to the other by reversing the skin upon itself. The jaws 2| and 22 are, by this action, driven together so that the skin is firmlycengaged during the entire pulling operation.

Ithas been found that. when the skin is pulled from a meat cut in this manner the skin is removed quite satisfactorily without damage to the meat structure itself or to the skin. As soon .as the skin is completely removed from the cut, the

pulling force against chain 28 is released and the clamp 20 is opened by spring 25 so that the skin may be released. As soon as the skin has been pulled from the cut, the carriage 30 reaches approximately the end of the track and the clamp and carriage may be lifted from the machine and returned to the starting point for attachment to a subsequent cut for skinning.

While one cut is in position and during the skin pulling operation being performed thereon in the machine shown in Figure l, a second cut may be engaged on the other pair of prongs I4 and 15. The tab [2 of this second cut may then be raised and engaged onto a clamp 20 so that as soon as the skin pulling process being performed, is completed, the head [6 may be shifted to move the skinned cut out of position and place the second out before slot 34 so that hook arm 8| of the clamping structure fixed to its skin, may be dropped into the pulling means. The movable head mounting means It for the pairs of prongs l4 and I5 makes it possible for one operator to utilize the machine to the fullest possible extent.

A modified form of the above described machine is shown in Figure 4 and in this device a bifurcated hook 50 as shown in Figure 6, is provided, having diverging arms for engaging the bone of the meat cut and a clamp 5| is also provided for fixing to the skin. The jaws 52 and 53 of the clamp are urged together by manipulation of arms 54 and 55 which in turn are so connected that when a pulling action is exerted against the clamp, the jaws are driven together. The arms 54 and 55 are interconnected by a link 56 which at one end, is pivotally connected to the arm 55 and at the other end, is slidably connected to arm 54 in a suitable slot. The sliding end of link 56 is connected to the chain 5'1 and any pull exerted on the link 56 by chain 51 causes the lower end of link 56 to slide to the left, as in Figure 4, so that arm 55 is pulled downwardly to drive the jaw 53 against jaw 52.

The clamp is slidably mounted in a movable carriage 60 carried upon the top frame of the machine in suitable slide ways, the clamp being slidable in the carriage on a guide way 6|. The carriage is adapted to be driven by a suitable power means such as the air motor I0 and the driven piston of the air motor is connected to the carriage through the connecting rod H, which is fixedly connected to carriage 60.

In the operation of the mechanism shown in Figures 4 and 5, the clamp 5| is attached to the skin tab 12 and then the power is supplied to the air motor so that the piston is driven to the left as shown in Figure 4. When the connecting rod 1| moves to the left, the carriage 60 is carried therewith. The clamp 5| remains stationary until the slack in the chain 51 is taken up whereupon continued movement of the carriage causes the jaws 52 and 53 to be engaged tightly on the skin flap so that further movement of the carriage causes a drawing action to be applied against the skin so that it is forcibly stripped from the meat cut engaged upon the hook 50.

The motive power to the motor 10 is controlled by a suitable air valve 12 located adjacent the working station of the machine and by suitable manipulation of the valve the piston and the air motor can be driven to the left or right to As above stated, the skin of a shoulder or ham cut is prepared for removal by freeing a tab of skin adjacent the outside of the shoulder or hip joint. The surface on the inside of the animal's leg is cut skin deep along a line substantially parallel to the femur or humerus bone disposed in the cut. a When the skin is prepared in this manner, the skin may be forcibly pulled off of the out without damage to the skin or the meat cut.

As shown in Figure l the out can be laid over on the table with the skin tab on top of the cut so that the clamp may be engaged on the tab and the skin pulled back upon itself as the clamp moves over the top of the out. In some instances, the cut can be more easily placed on the hooks if the cut is handled as shown in Figure 4. In this instance, the cut is merely placed on the hook 50 in such a manner that the skin tab I2 is adjacent the clamp and when the clamp is fixed to the tab the cut is allowed to fall over onto the clamp so that the enlarged end of the bone is engaged in the hook as the cut falls onto the clamp. Thereafter, as the clamp is driven out from under the cut, the skin is forcibly drawn off of the meat. The manner of engaging the meat cut on the hooks as shown in either Figures 1 and 4 may be used interchangeably with either form of the machine.

The above description of the machine shows its application to cuts of irregular shape. It is obvious that a flat cut could be fixedly engaged and its skin attached to one of the clamping means so that the skin could be drawn from the cut as described above. The machine is particularly adapted, however, to the removal of skin from irregular cuts such as shoulder and ham cuts where the meat may be separated from the skin by a mere pulling action.

In trimming certain cuts for the retail trade, it is the custom to leave a ring of skin around the hock or shank end of the cut. This may be accomplished in the present machine by cutting through the skin at the hook end before pulling the skin from the meat out. It is likewise apparent that the skin may be stripped from the cut by pulling it from the hock end toward the butt end. The preferred stripping, however, is as above described.

Many modifications of the invention disclosed herein may occur to those skilled in the art. While the invention has been described and illustrated with means for holding the cut stationary while pulling the skin, it is readily apparent that the skin could be fixed and the out moved. Figure 7 illustrates an embodiment of such machine. In this case the bracket which supports hook 50 is attached to chains 40 and 41 by means of cross bars 42 whereby the chains move the effect first a pulling off of the skin and thereafter hook 50 across the top run to the right in Figure 7. Clamp 20 is held in a relatively fixed position, i. e., restrained against movement to the right in Figure 7 by reason of chain 28 being fixed to the jrameof the machine as illustrated at 75.

The rotation of chains 40 and 41 may be any speed convenient to allowing the ham cut to be placed over hook 50 and the clamp 20 to be seecured to tab 12 of the cut. As the hook 50 rises to the top run at the left end of Figure 7, the ham cut 10 may he slipped down ,over the hook as previously described in connection with Figure 4. The clamp 20 may be secured to tab 12 on the skin either before or after the cut is engaged upon the hook v50.

As chains 40 and 41 move hook 50 and cut 10 to the right in Figure 7, the slack in chain 28 7 willrun out,- and asthe chain tightens the pull on tab 12 will strip the skin from the cut with the out being turned down into a horizontal position as the pull is applied. The position of the cut will be substantially that illustrated at the right-end ,of Figure 7.

The length of the machine may be any distance which will satisfactorily permit the meat cuts to be mounted on the hooks, the skin to be pulled therefrom, andthe cuts to be subsequently removed from the. hooks. The cuts may be removed after the skin has been stripped therefrom by lifting them up and by tipping them forwardly to disen age thebifurcated end of the hook 50 from the cut and bone thereof.

A single or plural grouping of pulling means maybe associated with clamping means to hold the cuts, but as shown in the preferred form of the machine as shown in Figures 1 and 2, a single pulling means is adapted to cooperate with a plurality of holding means. All such modifications are considered to be within the scope of the following claims.

I'claim:

1. A'machine for pulling skin from a meat out surrounding a bone having enlarged ends such as the humerus bone of a shoulder cut and the femur bone of a ham cut, comprising means to engage the bone of said out at one of the enlarged ends of the bone, a clamping means adapted to be fixedly secured to the skin, pneumatically driven means to pull the clamping means away fromsaid engaging means in a direction to pull the skin from the cut progressively from one end to the other, and means to connect the pneumatically driven means to the clamping means.

2. A machine for pulling skin from a meat cut surrounding a bone having enlarged-ends such as the humerus bone of ashoulder cut and the femur bone. of a ham cut, comprising means to engage the bone of said out at one of the enlarged ends of the bone, a clamping means adapted ,to be fixedly secured to the skin, and power driven endless chain means adapted for connection'with thezclamping means to pullthe clamping means away from said engaging means in a direction to pull the skin from the cut progressively from one end to the other.

3. A machine for pulling skin from ameat out surrounding a bone having enlarged ends, such as the humerusbone of a shoulder cutand the femur bone of-a ham cut, comprising a plurality of means [such]. each individually adapted to engage the bone of one of said cuts, all of said engaging means being mounted on movable supi porting means, means including a clamp adapted to be-fixedly secured to the skin of a cut, and a single driven means, said means including said clamp being adapted to be interconnected with said driven means, and said movable supporting gage the bone of one of said cuts at one of the enlargedends of the bone; said engaging each being fixed to a supporting means movable laterally across the frame of the machine; a clamping means adapted to be fixedly secured to the skin of a cut; said clamping means including a flexible link and a carriage connected to the end of the link; a slideway on the upper portion of the frame of the machine on which-said carriage is adapted to slide; said slideway having a slot therein extending longitudinally of said machine frame; a driven means disposed below said slot; means extending downwardly fromsaid carriage and adapted to pass through the slot to be engaged by said driven means; means on said driven means for cooperating with said downmeans beingv movable sothat an' engaging means having. the bone of a meat cut fixed thereto may be positioned in proximity to the driven means,

and said driven means being effective wheninterconnected with said clampingmeans to pull the clamping means away from said positioned engaging means in a direction to pull the skin from the out there engaged progressively from one end .to the other.

4.'A machine for pulling skin from a meat cut surrounding a bone having enlarged ends such as the humerus bone of a shouldercut and the femur bone of a ham cut, said machine being builtupon a suitable frame; comprising a plurality-of. means; each adapted to individuallyem wardly extending engaging means; ,said driven means being effective, when interconnected with said carriage through the engaging means, to drive the carriage along the slideway; and the supporting means for saidbone engaging means being movable laterally across the machine to position a cut engaged thereby in proximityto one end of said slot so that when the carriage is driven along the slideway, the clamping-means Will pull the skin from the cut progressively from one end of the cut to the other.

5. A machine for pulling skin froma meatcut surrounding a bone such as the humerus bone of a shoulder cut and the femur bone of a ham cut; comprising a pulling means to forcibly draw the skin from the out; and a holding means ;-to relatively fixedly engage the bone of said out; said holding means being adapted to be solidly supported in a position to cooperate with'the pulling means; said holding means includinga bifurcated means having diverging, arms to engage the bone behind the enlarged end thereof as the skin is being pulled-from the cut positioned in the holding means; and said pulling means having a clamping means adapted to be fixedly secured to the skin adjacent the holding. means; and said pulling means also including a power drive to pull the clamping means away from the holding means to progressively pull the skin from the cut.

6. A machine for pulling skin from a meat cut surrounding a bone such as the humerus bone of a shoulder cut and the femur bone of a ham out; comprising a pulling means to forcibly draw the skin from the cut; and a holding meansto relatively fixedly engage the bone of said cut; said holding means being adapted to;be sol-idly supported in a position to cooperate with the pulling means; said holding means including a bifurcated means having diverging arms toengage the bone behind the enlarged end thereof as the skin is being pulled from the cut positioned in the holding means; said pulling means having a clamping means adapted to be fixedly secured to the skin; said holding means and said clamping means being so positioned with respect to each other that said clamping means pulls the skin from underneath the out while reversing the skin upon itself; and said pulling means also including a power drive to pull the clamping means away from the holding means to progressively pull the skin from the cut.

7. A machine for pulling skin fromameatcut surroundinga bone having enlarged endssuch as the humerus bone of a shoulder cut and the femurgbone of a ham cut, comprising bifurcated secured to-the skin, and power driven endless chain means adapted for connection with one of said means to separate the clamping means from said engaging means in a direction to pull the skin from the .cut progressively from one end to the other.

8. A machine for pulling skin from a meat cut surrounding'a bone such as the humerus bone of a shoulder cut and the femur bone of a ham cut; comprising a pulling means to forcibly draw the skin from the cut; and a holding means to relatively fixedly engage the bone of said out; one of said means being adapted to be solidly supported in a position to cooperate'urith the other of said means; said holding means including a bifurcated member having diverging arms to engage the bone behind the enlarged end thereof as the skin is being pulled from the cut positioned in the holding means; and said pulling means having a clamping member adapted to be fixedly secured to the skin adjacent the holding means; and said other means also including a power drive to separate the clamping means from the holding means to progressively pull the skin from the cut.

9. A machine for pulling skin from a meat cut surrounding a bone such as the humerus bone of a shoulder cut and the femur bone of a ham cut; comprising a pulling means to forcibly draw the skin from the cut; and a holding means to relatively fixedly engage the bone of said cut; one

of said means being adapted to be solidly sup- 10 ported in a position to cooperate with the other ofjsaid means; said holding means including a bifurcated member having diverging arms to engage the bone behind the enlarged end thereof as the skin is being pulled from the cut positioned in the holding means; said pulling means having a clamping member adapted to be fixedly secured to the skin; said holding means and said clamping means being so positioned with respect to each other that said clamping means pulls the skin from underneath the out while reversing the skin upon itself; and said other means also including a'lpower drive to separate the clamping means from the holding means to progressively pull the skin from the cut.

' SWIFT AND COMPANY,

Assignee of Frederic J. Coad, Deceased,

By R. W. REGE'NSBURGER,

Vice President.

REFERENCES CITED following references are of record in the file of this patent or the original patent:

UNITED STATES PATENTS 

